Metastasis or dissemination of primary tumor cells is the major cause of mortality in cancer patients. Circulating tumor cells (CTCs) in the bloodstream are key players in the establishment of metastatic tumors. Recent studies demonstrated that the number of CTCs present in patient blood directly correlate with cancer progression, recurrence, and survival rate. Accurate detection of CTCs will provide critical information for proper management of cancer patients. Currently, the CellSearch(R) test is the only FDA-approved method for detection of CTCs in cancer patient blood. However, similar to all other antibody-mediated methods, this test requires multiple steps for sample preparation and cell labeling, which can cause loss of and damage to CTCs in blood samples and adversely affect the sensitivity and accuracy of the test. In addition, the requirement of multiple steps is time- and labor-consuming. In the proposed study, we aim to overcome these technical obstacles and develop a simple point-of-care assay by integrating a novel Tumor Cell-activation Aptamer Reporting system (TCAR) and innovative Spinning Disc Imaging Technology (iSDI). In contrast to current antibody-mediated multi-step tests, the TCAR system will be able to selectively highlight CTCs through natural cellular processes in whole blood within minutes using a single-step reaction. In addition, TCAR will provide no background or off-target signals and will not require a post-labeling cell wash. The iSDI technology will detect CTCs in a high-speed manner and record high-resolution images, similar to a Blu-ray disc player reading bits on disc. Compared to conventional automated fluorescence microscopes, the iSDI system is superior in sensitivity, speed, and operates at a lower cost. We hypothesize that this assay will be able to detect an accurate number of CTCs within minutes in whole blood samples through a single-step reaction, which will eliminate potential loss of and damage to CTCs in the samples. To test our hypothesis, three aims are proposed. We will optimize the TCAR system containing aptamer probes specific for EpCAM to selectively highlight carcinoma tumor cells in whole blood (Aim 1) while constructing and validating the iSDI system for coating, scanning, and imaging cells completely hands-free in minutes (Aim 2). In Aim 3, we will integrate the TCAR and iSDI systems, develop a point-of-care assay for rapid detection of CTCs, and validate the performance using tumor cells in normal human blood samples. We predict that this simple assay will provide high-definition morphology of CTCs along with their fluorescence identity in one step within minutes.